Scilab Function
Last update : 12/1/2004

g_margin - gain margin

### Calling Sequence

  `[gm [,fr]]=g_margin(h)`

### Parameters

- `h`: `syslin` list representing a linear system in state-space or transfer form

### Description

returns `gm`, the gain margin in dB of `h` (SISO plant) and `fr`, the achieved corresponding frequency in hz. The gain margin is values of the system gain at points where the nyquist plot crosses the negative real axis.

### Examples

    h=syslin('c',-1+%s,3+2*%s+%s^2)
    [g,fr]=g_margin(h)
    [g,fr]=g_margin(h-10)
    nyquist(h-10)

### See Also

`p_margin`, `black`, `chart`, `nyquist`,